Objectives Increased risk of herpes simplex virus 2 (HSV-2) has been proposed as a possible indirect pathway through which hormonal contraceptives (specifically depot medroxyprogesterone acetate (DMPA)) may increase the risk of HIV acquisition among women. We investigated the effects of DMPA on HSV-2 acquisition among female sex workers.
Methods Longitudinal data were drawn from a prospective cohort of sex workers in Vancouver, Canada. The primary outcome was HSV-2 seroconversion. Extended Cox regression analyses were used to model the independent effect of DMPA use on HSV-2 acquisition.
Results Between January 2010 and February 2014, 149 HSV-2 seronegative women were enrolled, contributing to 228 person-years (py) of follow-up. Of these, 19 (13.3%) reported DMPA use. There were 39 HSV-2 seroconversions (12 among DMPA users and 27 among non-users) over the study period (median follow-up of 18.6 months (IQR 8.4–29.9)), resulting in an overall incidence rate of 17.1 cases per 100 py (95% CI 12.4 to 23.6). Incidence rates were higher among DMPA users (57.4 cases per 100 py, 95% CI 31.4 to 105.0) compared with non-users (13.1 cases per 100 py, 95% CI 8.9 to 19.1). After adjusting for key confounders, use of DMPA remained an independent predictor of HSV-2 acquisition (adjusted HR 4.43, 95% CI 1.90 to 10.35).
Conclusions The high observed incidence rates of HSV-2, together with a strong association between DMPA exposure and HSV-2 acquisition, raise serious concerns about the provision of optimal reproductive and sexual healthcare to sex workers in this setting. Given the known links between HSV-2 and HIV, our findings underscore the need for further research to better understand the potential association between DMPA and increased risk of HSV-2 and other STIs to help inform the development of safer reproductive choices for women worldwide.
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Handling editor Jackie A Cassell
Contributors KS, MES and PD designed the study. PN did the statistical analysis. MES wrote the initial draft. All authors contributed to the interpretation of the findings, the critical revision of the manuscript for intellectual content, and approved submission of the final manuscript.
Funding This research was supported by operating grants from the US National Institutes of Health (R01DA028648) and Canadian Institutes of Health Research (CIHR, HHP-98835), and MacAIDS. KS is partially supported by a Canada Research Chair in Global Sexual Health and HIV/AIDS and Michael Smith Foundation for Health Research (MSFHR). JSGM is supported with grants paid to his institution by the British Columbia Ministry of Health and by the US National Institutes of Health (R01DA036307). MES is supported by a MSFHR postdoctoral fellowship award. PD is supported by CIHR and MSFHR postdoctoral fellowship awards.
Competing interests JSGM has received limited unrestricted funding, paid to his institution, from Abbvie, Bristol-Myers Squibb, Gilead Sciences, Janssen, Merck and ViiV Healthcare.
Ethics approval Providence Health Care/University of British Columbia Research Ethics Board (H09-0280).
Provenance and peer review Not commissioned; externally peer reviewed.
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